Every electrical device that connects with a power supply main is required not to pollute or transmit high frequency noise onto the main. The amount of electrical emission allowed by electrical devices is heavily regulated by the Federal Communications Commission (FCC). Conventional power supply designs have migrated to using higher operating frequencies since the higher operating frequencies allow a reduction in size of power supply components and allow a reduction in cost. The disadvantage of operating at higher frequencies is the increased production of higher order harmonics or electromagnetic interference (EMI).
Conventional methods of reducing EMI have been aimed at reducing a switching frequency of a switching circuit below standard EMI bandwidth limits of 150 KHz as set by the FCC. This approach has the disadvantage of increasing the size of magnetic components in a power supply. Other methods of reducing EMI have simply been to add additional filter components to reduce unwanted frequency harmonics. This second approach has the disadvantage of adding to the weight, size and cost of power supplies. Another approach to reducing large spikes of harmonics or EMI is the use of a snubber circuit. The snubber circuit although effective in reducing EMI, compromises efficiency of a power converter. In yet another approach, EMI is reduced by using jitter that takes a discrete harmonic spectrum and spreads the EMI over a continuous frequency range. Conventional systems use jitter by injecting noise into a gate drive or controller of the converter. Injecting noise into the gate drive of the converter has the disadvantage of distorting the output voltage signal. Further, injecting noise directly into a gate drive only applies jitter to the rising and falling edges of the converter switching signal. Moreover, because the jitter is continuous throughout the cycles of the switching signal, is outside the bandwidth of the amplifier and is injected outside the regulation loop of the switching circuit, it causes unwanted high ripple on the output of the switching circuit. Accordingly, by continuously injecting jitter directly into the gate drive circuit, conventional power converters inhibit the efficiency of feedback loop and other features including zero voltage switching and sampling of the switching signal.